1. Field of the Invention
The present invention relates to a first type of method for producing a connector that is made from at least three parts. The connector connects a fluid line to an opening of a component that is made of a thermoplastic material. A first part of the connector is formed from an essentially thermoplastic material. A second part and a third part of the connector are each formed from an essentially thermoplastic material and are fused together so that they are connected in a fluid-tight manner. The material of the third part is selected so that it is capable of forming a fusion connection with the thermoplastic material of the component.
The present invention also relates to a second type of method for producing a connection that is made from an essentially thermoplastic material. The connector connects a fluid line to an opening of a component that is made of a thermoplastic material;
2. Discussion of the Related Art
German Reference Nos. DE 195 35 413 C1 and DE 42 39 909 C1, each discloses a process of the first type mentioned above in which the parts of a connector are produced by spraying or injecting a thermoplastic material onto, around or in the same mold to form a connected first and second part. The first part, to which the fluid line (e.g., a rubber hose or a flexible plastic line) is normally attached, can, according to the intended use, have any of a number of different shapes. For example, the first part, according to the use of the connector, can be a straight tube piece or bent at a large number of angles. In addition, the first part may have holding ribs, which also can be of various shapes and be present in various numbers. In contrast, the second and third parts always have the same form, independent of the form of the first part. Therefore, different molds must be produced according to the particular required form of the first part. But producing a different mold for the combined first and second parts of the connector is expensive.
German reference DE 195 46 188A1 discloses a process of the second type mentioned above in which the connector parts are produced as one part and are formed in one piece with the component. Because the parts of the connector are produced in one piece with the component, the structural requirements (e.g., strength, impact resistance, creep and diffusion) of the component are satisfied. But, during use, the connector may be exposed to higher loads, such as, for example, significant surface pressure when a fluid line is attached to the connector. Over time, especially if the connector is exposed to relatively higher temperatures, the parts of the connector can become permanently deformed. Also, producing the connector in one piece with the component requires the use of an expensive mold.
It is an object of the present invention to provide simplified processes for producing a connector.
This and other objects of the present invention are achieved in accordance with a first solution for a process of the first type by connecting the first part and the second part of the connector outside of a mold.
In accordance with a presently preferred exemplary embodiment of the present invention, the first part is produced in its own mold and the second and third parts together are produced in their own mold. To produce the various required shapes of the first part, only the first part mold has to be separately produced to correspond to the various shapes. In contrast, the mold that is used jointly for the second and third parts, remains unchanged and, therefore, only has to be produced in one shape. Thus, the overall cost for producing a connector with the molds in accordance with the present invention is significantly reduced.
The first and second parts may be bonded, for example by fusion. The fusion connection can be made by hot plate welding (also called xe2x80x9cbutt-fusion using hot plate weldingxe2x80x9d), ultrasonic welding, or rotation welding (i.e., friction welding).
Alternatively, the first and second parts can be connected in a form-locking (or form-closing) manner such as, for example, by a snap, bayonet, or threaded connection.
To simplify the production of fusion connections and form-locking connections, a surface of the first part and a surface of the second part that are to be connected may be shaped before being connected so that they will mesh with each other.
To render the connection between the first and second parts as impervious as possible, a seal may be placed in a plane between the surfaces of the first and second parts that are to be connected.
The second part may be formed so as to extend through the third part beyond the side of the third part, which side faces the component. The second part can then be introduced into the opening in the component to center the connector with respect to the opening. The material that the second part is made from can be chosen to protect the connector against corrosion and/or diffusion of the fluid (e.g. fuel or oil for a combustion engine) fed through the connector.
At least one of the second part and the third part may be formed so as to be impervious to diffusion.
The first part is, in one embodiment, produced with at least one layer provided thereon. The first part and the at least one layer may be made of materials having different properties with respect to their strength, impact resistance, and tendency to creep. Thus, there is a relatively wide range of selection for the thermoplastic material of the first part. For example, the first part material can be selected so that it can be fused, in a relatively simple manner, to the material of the second part. The first and second parts can be made from the same material. In contrast, the material of the at least one layer should meet a large number of requirements for the combination of the at lease one layer and the first part, such as, for example, strength, impact resistance, tendency to creep and sealing against diffusion. Thus, the first part is, in one embodiment, produced with at least one metal layer because metal provides high sealing effectiveness against diffusion.
In an alternative embodiment, the at least one layer can be made of plastic, and at least one of the first part and the at least one layer is reinforced.
The at least one layer may be formed on the inner side of the first part and extend over the axial length of the inner side of the second and third parts on the inner side of the second part. Thus, with an appropriate selection of the material of the at least one layer, the second and third parts are protected by the at least one layer.
The second and third parts may be formed by injection-molding in a common mold and are formed to be rotationally symmetrical. Because the part to be formed is rotationally symmetrical, the formation of the mold is simplified.
The first part and the at least one layer are preferably formed by a multi-component injection or a sandwich-injection molding process. Thus, a relatively simple mold can be used to produce the first part and the at least one layer.
A fourth part is, in one embodiment, fused onto the third part, on the side of the third part facing away from the second part. The fourth part may be made of a thermoplastic material that is capable of forming a fusion connection with the component. The fourth part may have a higher resistance to tension cracks than the third part. Because the component to which the connector will be fused is typically made of a plastic that has a high resistance to cracking, making the fourth part of a higher resistance material ensures that if a higher tension load is applied on the component, the fusion connection between the connector and the component will not be broken nor will a tension crack be created in the connector.
The material of the fourth part preferably has a higher density and viscosity than the density and viscosity properties of the material of the third part.
In accordance with a second solution for a process of the second type, the object of the present invention, and other objects, are achieved by making the connector from an outer part, an inner layer and an intermediate layer in an injection-molding process. The outer part and the inner layer, on the one hand, and the intermediate layer, on the other, are made of materials with different properties, especially with respect to strength, impact resistance, and tendency to creep. At least one of the outer part, the inner layer and the intermediate layer is formed so as to be impervious to diffusion. Thus, in accordance with this solution, a connector having a complex shape can be produced in a simple manner, whereby the materials of the outer part and the layer(s) on the inner side of the outer part are selected so that the connector meets all structural requirements of the connector. The injection-molding process is preferably a sandwich, monosandwich, push-pull, or coinjection injection process. Another intermediate layer may be disposed between the first outer part and the inner layer. The intermediate layer is preferably a coupling agent.